This invention deals with means including an ink fountain and forming parts of an inking mechanism for printing presses, particularly those having a printing plate wrapped around a plate cylinder. More particularly, the invention concerns ink supply means suitable for "keyless" printing, by which is meant the printing processes that demand no control of ink supply to suit specific density distributions as required by the images on the printing plates but that need only ink film of constant thickness at all times.
Japanese Unexamined Patent Publication No. 9-226095 is hereby cited as teaching an ink supply apparatus closest to the instant invention. This prior art apparatus includes an ink fountain having an open side closed by a fountain roller, which is therefore constantly directly exposed to the ink in the fountain. The ink is transferred from the fountain roller to a knurled cylinder via one or more ink rollers, from which knurled cylinder excess ink is doctored off and back into the ink fountain. Ink transfer from the knurled cylinder to the printing plate on a plate cylinder is accomplished, typically, by two ink rollers each in rolling contact with both knurled cylinder and plate cylinder. Ideally, the ink film thus formed on the plate cylinder is of constant thickness throughout its axial dimension.
Further, according to the prior art, the ink fountain has its bottom formed, either in part or in whole, by a blade movable into and out of abutment against the surface of the fountain roller to close and open the ink outlet therebetween. Drive means are mounted to the ink fountain for linearly moving the blade toward and away from the fountain roller.
Difficulties have been experienced, however, in moving the fountain bottom blade into neat, leak-free contact with the fountain roller, particularly in usual cases where the blade, and of course the fountain roller as well, are elongated axially of the fountain roller. In such cases there have been provided two or more drive mechanisms in spaced positions along the fountain roller axis. The noted prior art teaches the use of drive mechanisms that are independently adjustable for moving the blade parallel to the fountain roller. Such adjustable drive mechanisms are complex and costly in construction, inherently susceptible to troubles and malfunctionings because of precise synchronization sought after, and have required much time and labor for repair and maintenance.
As an additional disadvantage, even when themselves functioning normally, the drive mechanisms have been easy to cause uneven travel of the blade due to differences in load thereon. Ink has often leaked from between the blade and the fountain roller when, with the cessation of printing operation, the former is forced into contact with the latter because of nonparallel relationship therebetween.